Multi-layer type fusing boat



April 14, 1970 CHAN H. WANG MULTI-LAYER TYPE FUSING BOAT Filed OOt.'3l.1966 INVENTOR Chan H. Wang ATTORNEY United States Patent 3,506,426MULTI-LAYER TYPE FUSING BOAT Chan H. Wang, Mountain View, Calif.,assignor to Texas Instruments Incorporated, Dallas, Tex., a corporationof Delaware Filed Oct. 31, 1966, Ser. No. 590,985 Int. Cl. C03b 23/20U.S. Cl. 65-156 3 Claims ABSTRACT OF THE DISCLOSURE The multi-layerfusion boat comprising a bottom plate with cavities for each element tobe assembled and an aligned lead holding plate with geometrically shapedperipheral elements enclosing groups of leads in specific relationshipand an aligned cover plate with glass port delivering means for theassembly.

This invention relates to glass-to-metal seals and more particularly toa fusing boat for manufacturing headers for semiconductor devices.

A header, a support platform for a semiconductor device, is commonlyformed by sealing glass to metal leads and to a metal eyelet. A holder,or fusing boat as it is sometimes called, is used to hold the componentparts of the headers in the desired relationship to each other until theglass-to-metal seal is formed.

An object of this invention is a fusing boat for forming glass-to-metalseals that does not deteriorate with use.

Another object of the invention is a fusing boat for formingglass-to-metal seals that can be cleaned of glass buildup.

A further object of the invention is a fusing boat for formingglass-to-metal seals that does not contaminate the glass-to-metal sealto form bubbles at the glass-tometal interface.

The novel features believed to be characteristic of the invention areset forth in the appended claims. The invention itself, however, as wellas further objects and advantages thereof, will best be understood fromthe following detailed description of an illustrative embodiment thereofwhen read in conjunction with the accompanying drawing wherein the solefigure is a perspective representation of the two complementary sectionsof a fusing boat according to the invention, including a number ofheader components in between the two sections of the boat.

Referring to the drawing, a preferred embodiment of the fusing boat ofthe invention comprises a bottom section 1 made of metal, preferablyKovar, a trademarked nickel cobalt alloy of iron manufactured by theWestinghouse Electric Company. Said section has a number of eyeletseating slots 2 (eight by way of example, as shown in the drawing) inwhich to hold the eyelets 3 of the headers in relationship to the leads4 of said headers, which leads are connected together in a lead frame 5,both the frame 5 and the leads 4 being made of the same metal or alloyas the sections 1 and 8 of the fusing boat to insure the samecoefficient of expansion between the fusing boat and the headers. Thelead frame 5 has precisely located holes 6 which locate on the posts 7of the bottom section 1 of the boat. The top section 8 of the boat haslocating holes 9 which also locate on posts 7. Therefore both sections 1and 8 of the boat, eyelets 3 and lead frame 5 are precisely aligned witheach other. The top section 8 of the boat has eight apertures 10 toallow weights (not shown) to be placed on top of the eyelets 3 whenrequired.

A pressed glass pellet (not shown) or a glass slurry (not shown) isplaced in each eyelet 3 after the leads 4 "ice are located in the eyeletso that the leads extend through lead openings (not shown) in theeyelets 3. The assembly of eyelets 3, lead frame 5 and the glass isplaced on the bottom section 1 of the boat with the eyelets open-end upin the eyelet seating slots 2, such that the locating posts 7 passthrough the locating holes 6 of the lead frame 5. The top section 8 ofthe boat is then placed over the assembled lead frame and eyelets byaligning the 10- cating holes 9 with the locating posts 7. A weight (notshown) is then placed in each aperture 10 of the top section to aid informing the glass-to-metal seal when the glass pellet is used but is notrequired with the glass slurry.

The assembled boat and header components are made to travel through aconventional header fusing furnace for about one hour, during which timethe glass melts to form glass-to-metal seals to the eyelets and leads.The Kovar boat is virtually unaffected by the furnace conditions so thatit has very extended life. Because the Kovar does not deteriorate withuse it is not a source of contamination thereby allowing almostbubble-free glass-tometal seals. Any glass that has fallen on thesurface of the boat can be easily removed with a dilute hydrofluoricacid etch without harming the boat. Since the boat is made from the samemetal as the metal components of the header there is a perfect thermalexpansion match of the boat and header during the sealing operationwhich increases the dimensional control of the header.

Although a preferred embodiment of the invention has been described indetail, it is to be understood that ohvious changes, substitutions, andalterations can be made therein without departing from the spirit andscope of the invention as defined by the appended claims.

What is claimed is:

1. A header fusing boat for releasably holding a metal lead frame, suchas the type having groups of metal leads and respective metal eyelets,in relative position, and for making glass-to-metal seals between thegroups of leads and respective eyelets, comprising in combination:

(a) a geometrically shaped metal bottom section hav- (1) a plurality ofgeometrically shaped slots formed on one surface thereof, and (2) aplurality of spaced posts extending from said one surface; (b) ageometrically shaped metal lead frame contiguous with said bottomsection and having 1) a plurality of groups of leads, with each group ofleads extending toward and into a respective geometrically shapedeyelet, and (2) a plurality of spaced openings formed therein, each ofwhich is coaxially aligned with and positioned upon a respective one ofsaid posts on said bottom section, wherein (3) said eyelets arerespectively positioned within said slots in said bottom section; and(c) a geometrically shaped metal top section contiguous with said leadframe and having (1) a plurality of geometrically shaped openings formedtherein, each of which circumscribes a respective eyelet of said leadframe, and (2) a plurality of spaced openings formed therein, each ofwhich is coaxially aligned with and positioned upon a respective one ofsaid posts on said bottom section; wherein (d) said bottom and topsections releasably hold said eyelets in a predetermined position withrespect to said groups of leads. 2. The header fusing boat of claim 1wherein: (a) said bottom and top sections and said lead frame arerectangular shaped; and

. 3 4 (b) said slots of said bottom section, said geometric 3,310,3923/1967 Rhodes 65-154 openings of said top section and said eyelets ofsaid 3,317,106 5/1967 Dix 65-154 XR lead frame are rectangular shaped.3. The header fusing boat of claim 1 wherein said FOREIGN PATENTS bottomand top sections and said lead frame are made 5 347,724 1886 yf k1 bltllo of'o. me e co a a y n FRANK W. MIGA, Primary Examiner ReferencesCited UNITED STATES PATENTS 911,678 2/ 1909' Quertinmount 65154 13,299,502 1/1967 Wanesky 65-155 XR US. Cl. X.R.

